When silver halide photographic materials are exposed to light and then subjected to color development processing, aromatic primary amine developing agents oxidized by silver halide are reacted with color couplers, whereby color image can be formed.
As yellow couplers, there are known four-equivalent type couplers and .alpha.-acylacetanilides where one hydrogen atom of active methylene group is substituted by an aryloxy group, a halogen atom, sulfoxy group, an acyloxy group, etc., described in JP-A-50-87650 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), U.S. Pat. Nos. 3,369,695, 3,408,194, 3,415,652 and 3,447,928. These couplers have disadvantages in that coupling reaction activity is low and image fastness is poor.
When color formability is insufficient, there are problems that photographic characteristics are greatly varied by changed in the components of developing solutions and images of stable quality can not be obtained. When image fastness is poor, the quality of image is deteriorated during storage. Thus, it is highly demanded to improve image fastness.
As yellow couplers which are more active and freed from the above problems, there are known couplers wherein one hydrogen atom of active methylene group is directly substituted by a nitrogen-containing heterocyclic ring, described in JP-A-47 26133.
However, when these couplers are used, yellow color image is not considered to be fully satisfying with respect to fastness under light and moisture and heat conditions, though formability is improved.
It is highly demanded to reduce the amount of washing water or stabilizing solution from the viewpoint of the preservation of the environment. When the amount is reduced (for example, by a method described in JP-A-57-8543), image fastness is greatly deteriorated. Thus, it is eagerly demanded to find out a method for improving yellow image fastness.
Hindered amines and hindered phenol compounds are described as stabilizers for yellow image in British Patents 1,326,889, 1,354,313 and 1,410,846.
However, effects obtained by these compounds are still unsatisfactory, though the fastness of yellow image is somewhat improved.